Electrical cooking appliance, in particular deep fryer, comprising a flat heating element with screen-printer resistor

ABSTRACT

The invention concerns an electrical cooking appliance comprising, in a housing ( 12 ), a sheet metal bowl ( 14 ) coated on its inner ( 25 ) and outer ( 26 ) surfaces with a heat-resistant coating, and electrical heating means ( 16 ) associated with the bowl ( 14 ) and comprising a flat heating element ( 18 ) with screen-printed resistor ( 37 ). The invention is characterized in that the outer surface ( 26 ) of the bowl ( 14 ) base ( 30 ) has a zone ( 32 ) not provided with the coating ( 28 ) and on which is directly mounted the flat heating element ( 18 ) The invention is applicable to electric deep fryers in particular.

The present invention relates to electric cooking apparatus for foodwhich comprises, in a housing, a cooking vat of sheet metal covered onits internal and external surfaces with a heat resistant coating,mounted fixedly or removably, and electrical heating means associatedwith the vat and comprising a flat heating element with aserigraphically applied electrical resistance.

It is applicable particularly but not exclusively to electric deep fatfryers for cooking, in an oil bath in particular, foods such as friedpotatoes, fish or meat.

It is known that for such food cooking apparatus, the cooking vat isgenerally made by stamping a plate of sheet aluminum or steel, and isthen covered internally and externally with a heat-resistant coating,generally of enamel. As is well known, such an enamel coating applied tothe internal and external surfaces of the sheet metal cooking vat,whether fixedly or removably mounted in the housing of the apparatus,permits in an advantageous way facilitating the cleaning of the vat,preventing oxidation of the sheet metal, and avoid adherence offoodstuffs to the internal surface of the vat.

In a known cooking apparatus of this type, the flat heating element withserigraphically applied electrical resistance is heated in a cutoutprovided in the bottom of the enamel sheet metal vat. Although thissolution permits overcoming the difficulty remaining to the present timeas to the technical drawbacks of serigraphically applying a heatingelement to a plate or sheet metal, it remains equally complicated andburdensome both as to production of the heating vat and as to the modeof securement of the heating element.

The invention has particularly for its object to overcome thesedrawbacks and to provide an electric heating element, of the typedescribed above, which will be of simplified design and less costlyproduction, whilst keeping the advantages arising from serigraphicallyapplying the heating element, such as particularly a very rapid increasein temperature of the cooking vat and good homogeneity of thedistribution of the temperature of heating.

According to the invention, the external surface of the bottom of thevat has a region which is free of coating and to which is secured theflat heating element.

Thus, the fact of removing the coating of this external zone on thebottom of the vat so as to fix the flat heating element there, hardlychanges the production of a conventional sheet metal cooking vat coveredinternally and externally with this coating, such as an enamel sheetmetal vat, and also permit a substantial saving in the materialconstituting the coating of the vat, in particular for mass production.

According to a preferred embodiment, the flat heating element isconnected by welding or cementing on the region free from coating.

The characteristics and advantages of the invention will become moreapparent from the description which follows, by way of non-limitingexample, with reference to the accompanying drawing, whose single FIGUREis a simplified transverse cross-sectional view of an electric cookingapparatus according to the invention, comprising a flat heating element,on an enlarged scale.

In the embodiment shown in the FIGURE, the electric food cookingapparatus 10 is an electric deep fat fryer, for example of generallyrectangular shape, comprising, in a housing 12 made of a plasticmaterial such as for example polypropylene, a rectangular vat 14 mountedfixedly or removably and adapted to contain a cooking bath (not shown)constituted for example by oil, as well as electrical heating means,designated by the general reference numeral 16, associated with the vat14 and comprising, as will be described in greater detail later, a flatheating element 18 with serigraphically applied electrical resistance.

In a preferred embodiment shown in the FIGURE, the cooking vat 14 ismounted removably in the housing 12, and to this end rests by bearingwith its upper peripheral edge 20, on a plurality of supports 21 mountedfixedly on the upper peripheral edge 23 of the housing 12 and made of athermally insulating material resistant to the temperatures of useduring frying.

In the FIGURE, the rectangular vat 14 is a piece of stamped sheet metal14 a, of aluminum or steel, which is covered on its internal surfaces 25and external surfaces 26 with a coating 28 resistant to heat, such asfor example enamel.

According to the invention, the external surface 26 of the flat bottom30 of the vat 14 has a region 32 which is free from coating 28, hencewithout enamel in this example, and to which is applied the flat heatingelement 18.

In a conventional manner, this external non-enameled region 32 isobtained by means of a mask applied during the enameling operation ofthe interior and the exterior of the vat.

In the embodiment shown in the FIGURE, the non-enameled region 32, whichis to say of sheet metal, of the external surface 26 of the bottom 30 ofthe vat, constitutes the major portion of this external surface 26 ofthe bottom of the vat 14.

The flat heating element 18 is connected to the external non-enameledregion 32 of the bottom 30 of the vat by any suitable securement means,and preferably by welding or cementing.

According to a preferred embodiment shown in the FIGURE, the flatheating element 18 is of small thickness and comprises a plate ofstainless steel 34 fixed on the non-enameled external region 32 of thebottom 30 of the vat 14, by means of a layer 35 of electricallyinsulating material disposed by serigraphy on the plate 34, and by meansof a resistive path 37 which is serigraphically applied over almost allthe surface of the layer 35 along a pattern of curves fitted within eachother, and which is protected by another layer 39 of electricallyinsulating material applied by serigraphy. There is shown at 41 in theFIGURE one of the two conductive tablets to which is secured one of thetwo electrical connections (not shown) of the heating element, and whichis also applied by serigraphy on the layer 35.

This flat heating element 18 moreover comprises a thermal regulatingmeans 43, such as a thermostat, which is mounted on the internal surfaceof the plate 34 (in the position shown in the FIGURE) by means ofsuitable securement means, such as for example screws.

The flat heating element 18 can also comprise several serigraphicallyapplied resistive tracks 37 of different powers which are suppliedseparately by means of a switching member (not shown) so as to selectthe suitable heating power according to the type of foodstuff to becooked.

Thanks to the absence of enamel in the external region 32 of the bottom30 of the vat 14, the serigraphically applied heating element 18 istherefore fixed in a simple manner to this region 32 and thereforesupplies a high localized heating power distributed rapidly anduniformly below the bottom of the vat 14, ensuring a very rapid rise intemperature of the vat. Moreover, the transverse thermal conductivity ofthe resistance 37 serigraphically applied on the stainless steel plate34 is very low, which permits advantageously limiting the risk ofheating the sidewalls of the vat 14.

There has thus been produced according to the invention an electricalheating apparatus for foodstuffs, in particular a deep fat fryer, whichis particularly advantageous not only from the standpoint of its thermalefficiency but also from the standpoint of its simplified design.

What is claimed is:
 1. Electric cooking apparatus, comprising, in ahousing (12), a sheet metal cooking vat (14) covered on its internalsurfaces (25) and external surfaces (26) with a heat resistant coating(28), mounted fixedly or removably, and electric heating means (16)associated with the vat (14) and comprising a flat heating element (18)with serigraphically applied electrical resistance (37), characterizedin that the external surface (26) of the bottom (30) of the vat (14) hasa region (32) which is free from said coating (28) and on which issecured the flat heating element (18).
 2. Apparatus according to claim1, characterized in that the region (32) of the external surface (26) ofthe bottom (30) of the vat which is free from coating (28) constitutesthe major portion of this external surface (26).
 3. Apparatus accordingto claim 1, characterized in that the flat heating element (18) issecured by welding or cementing on the region (32) free from coating(28).
 4. Apparatus according to claim 1, characterized in that it isconstituted by a deep fat fryer (10).